#include <iostream>

int swap(int *p1, int *p2)
{
    int tmp = *p1;
    *p1 = *p2;
    *p2 = tmp;
    
    return 0;
}

int swap2(int &n1, int &n2)
{
    int tmp = n1;
    n1 = n2;
    n2 = tmp;
    return 0;
}
int main()
{
    int a = 3, b = 5;
    int *pa = &a;
    int *pb = &b;
    // swap(pa, pb);
    swap2(a,b);
    std::cout << a << b << std::endl;
    return 0;
}